Automatic spark plug switch



June 23, 1953 p. H. SAUNDERS AUTOMATIC SPARK PLUG SWITCH Filed Aug. 2'7, 1952 lllflllll- Davis H. S aundevs Patented June 23, 1953 UNITED STATES PATENT OFFICE 2,643,275, V V AUTOMATIC SPARK'PLUG SWITCH 1 Davis H. Saunders, Maquoketa, Iowa Application August 27, 1952, Serial No. 306,666

My invention is an automatic switch responsive to engine load requirements that switches the timed electrical impulse of the ignition system to a widely or narrowly gapped spark plug in accordance with the demands of the engine.

In the early period of development in the automotive industry when cars were widely used but equipped with relatively low compression engines, the problem of what gap at which to set the electrodes of the spark plug was easily solved. When the first commercially available high compression engines were produced, however, a dilemma began to appear; and with the present very high compression engines the problem of what gap setting to use in adjusting the electrodes of the spark plugs has become acute. The best solutions appear to be compromises.

Most engines idle and operate better under no or low load conditions if the spark plug gap is set wide. On the other hand when the engine is operated under conditions that require it to deliver maximum torque as when it is operating under load conditions, the engine performs more effectively if the spark plug electrodes are set near to each other. Thus an engine which has the spark plugs adjusted properly for the best operation of the engine in slow traffic does not pull hills well. Likewise, however, the engine that is equipped with spark plugs that are set for best performance under heavy loads causes the engine to run roughly when the vehicle is stationary as at a stop light. Consequently most spark plugs are set to a compromise clearance that permits fair operation under all engine operating requirements.

These compromise settings have their drawbacks, however. The setting of the plug electrodes at wider than optimum gaps for load conditions causes very high voltages to be necessary in order to cause the spark to jump the gap in.

a cylinder in which the charge of gas and air has reached a high value. The voltage becomes so great that the insulation of the plugs is subjected to considerable electrical stress and breaks down altogether at the slightest provocation. Even the best plugs are apt to have a rather short life in very high compression engines. Also, of course, an engine which idles roughly is not making the best use of the gasoline and air mixture being placed in the cylinders at that speed, and some loss of torque is experienced under heavy load conditions also. when a compromise spark gap is used.

In view of the foregoing, therefore, it is the principal object of my invention-to .providean' 7 Claims. (01. 123148) automatic spark plug switch that will direct the timed ignition spark to a spark plug electrode gap of the proper size for the engine requirements at under any given load conditions. It is a further object of my invention to provide a spark plug switch that will improve engine operation at all speeds and loads.

It is a further object of my invention to pro vide a spark plug switch that will increase the useful life of spark plugs.

It is a further object of my invention to provide a spark plug switch that will provide a more efficient, and, therefore, more economical use of fuel.

It is a further object of my invention to provide a spark plug switch that will reduce ignition troubles to a minimum.

These and other objects will be apparent to those skilled in the art.

My invention consists in the construction, arrangement, and combination of the various parts of the device, whereby the objects contemplated are attained as hereinafter more fully set forth, and specifically pointed out in my claims, and illustrated in the accompanying drawings, in which:

Fig. l is a side elevation view of an internal combustion compression ignition engine equipped with my automatic spark plug switch. The distributor, coil, and my switch are shown in disproportionately large scale for clarity.

Fig. 2 is an enlarged vertical sectional view of my automatic spark plug switch.

Fig. 3 is an enlarged cross-sectional view of my automatic spark plug switch taken on the line 33 of Fig. 2 and with broken lines showing hidden parts and dotted lines showing an adjusted position of the switch contact plate which is assumed at high load conditions when manifold vacuum is low. Solid lines illustrate the position of the device when manifold vacuum is high as at idling.

Referring to the drawings, I have used the numeral It to designate a high compression engine that is equipped with the usual fuel air induction system- (not shown) and the usual breaker point timing ignition assembly enclosed in a customary housing designated I 2. The usual distributor finger 14 carries the brush I6 that maintains the high tension contact with the secondary coil of the coil unit [8. A conventional wire or lead 20 carries the high voltage current from the coil to the contact 22 that engages brush i6. Spaced around the distributor finger are a plurality "of contacts designated 24 which washer assembly designated 44.

at behind the diaphragm are very similar to the usual contacts in the ordinary distributor caps. Instead of connecting to ordinary ignition wires that lead to the spark plugs in the various cylinders, however, the contacts 24 merely project through the special breakor assembly housing cap 26. Also mounted in cap 26 are a series of similar contacts designated 28 and another series designated 30. To each of these contacts in series 28 are lead wires designated 32 while the numeral 34 designates the wires connected to the contacts 30. Leads or wires 32 extend to the various cylinders as do the lead 34. One wire from each group extends to each cylinder and connect either to separate spark plugs or to separate insulated gap structures in a single plug, Dual electrode plugs have been known in the past and also engines have been equipped with two spark plugs in each cylinder. I have used the two spark plugs per cylinder 4 arrangement in this case, but the important fact is that two or at least two difierent spark gaps are available in each cylinder. The plugs connected to leads 32 are designated 36 and are set to a close gap such as fifteen thousandths of an inch. The plugs designated 33 on the other hand are set to have a forty thousandths inch or otherwide gap and are connected to leads 3 5. Above the capis the switch plate 40 which serves to support the contact plates 42. insulated from each other and merely serve 'to connect the contacts 24 to the contacts 22 and til. The switch plate 40 is mounted for at least limited rotative movement with respect to top bolt, nutand An arm i6 is ivotallysecured to the switch plate it in any suitable manner as by the rivet BS. The arm also connects to the diaphragm 56 in the housing 52. The housing 52 has an air-tight chamber 56 and this chamber is connected by any suitable conduit such as the one designated 53 in Figs. 1 and 2. The conduit in any suitable manner as by the is connected to intake manifold of the engine it.

This connection is not shown in the drawings but is so well known as to-not require illustration for anyone familiar with the art. While I have shown a vacuum means for moving the switch plate, I am aware that devices related to engine torque or other 'manifestations of heavy load 'could be'u'sed to control my switch. The structural description having been completed I turn to a recitation as to the advantages and operation of my switch.

Before the engine is started or during heavy load conditions manifold vacuum is nearly equal to atmospheric air pressure which means that diaphragm 56 is subjected to the same or substantially the same pressures on both sides. Any

suitable yielding means such as a spring or the like then urges the diaphragm 50 to the left as viewed in Fig. 3. The contact plates 42 assume the positions shown in part by the broken lines. .The contacts 25, 23 and 30 are connected together, therefore, by one of the plates 42 forea'ch group. Since the contacts 28 are connectedto narrow gaps, they will be fired under these conditions. The voltage of coil l8 will also be applied to the widegaps connected to lead. If

the narrow gaps should fail to be fired because of high resistance in the line, the forty thousandth gap, or plugs will serve as substitutes.

Thus an oil fouling of the narrow gap will cause vthe wide gaps to fire until the narrow gapis cleared. As soon the less resistant gap has These plates are 4 been cleared by the burning of gas and air in the cylinder, the narrow gap will be fired again.

When the pressure in the intake manifold is much less than atmosphere is as is true at idling and when the engine is being used as a compression brake, the chamber 52 is subjected to this manifold vacuum and atmospheric air pressure moves the diaphragm 50 to the right as viewed in Fig. 3. The linkage 4B connecting the diaphragm 50 to the switch plate iil causes the plate to be moved to the solid line position shown in Fig. 3. When the switch plate is in this position, the contacts 24 are connected to the contacts 30 only. Only the wide gapped plugs are presented with a cylinder charge firing spark. The engine is in effect provided with a single set of plugs that are gapped for best engine operation at no load with the engine severely throttled as at idling. It is clear, therefore, that I have provided a means for changing from widely to narrowly gapped plugs and that the change is made automatically. Furthermore, the change is made in accordance with engine operation requirements. Because the correct best spark gap is used in each case, the plugs themselves will last much longer. There will be fewer insulation failures, for example, and less electrode wear resulting from high voltage. Obviously there will also be more efficient engine operation which means more economical use of fuel. Also, of course, considerable vibration will be avoided with a consequent saving in fatigue of structural parts all over a vehicle or stationary engine.

Although no separate stops are shown to limit the movement of the switch plate, the limits of movement imposed by the nature of the diaphragm do limit the extreme positions of the plate to avoid the possibility of completely breaking the circuit between the ignition coil and the spark plugs. From the foregoing it should be clear that I have invented an automatic spark plug switch that will achieve the objects of my engine a variable gap spark plug system com- I prising, two mutually insulated spark gaps in each cylinder of said engine, an ignition coil, a

breaker anddistributor finger assembly timed to said engine and electrically connected to said ignition coil, a top-for said breaker and distributor finger assembly having a plurality of contacts therein evenly spaced around said distributor finger and adjacent to the path described by the end of said distributor finger, a plurality of spark plug contacts arranged around said top; said spark plug contacts being twice as numerous as said distributor contacts, leads connecting the spark plugs in each cylinder to adjacent ones of said spark plug contacts, a switchplate 'moveably secured to said top, a plurality of contact plates secured to said switch plate; each of said contact plates selectively connecting both of the spark plug contacts for. one cylinder to one of said distributor finger contacts and only one of said spark plug contacts to said distributor finger contact, and-a means operatively associated with U said engine and said switch plate for selectively moving said switch plate.

2. In an automatic spark plug switch for use with an ignition breaker and distributor finger assembly, a top adapted to being secured to an ignition breaker and distributor finger assembly, a plurality of distributor finger contacts secured to and extending through said top, a, plurality of spark plug contacts secured to said top and being twice as numerous as said distributor finger contacts; one of said distributor finger contacts and two of said spark plug contacts constituting a group, a switch plate moveably secured to said top, a plurality of contact plates secured to said switch plate and each selectively contacting all the contacts of one group or omitting one spark plug contact from each group, and a means sensitive to engine load requirements secured to said top and said switch plate and producing relative movement therebetween in response to changing conditions of engine load.

3. In combination with an internal combustion engine a variable gap spark plug system comprising, two mutually insulated spark gaps in each cylinder of said engine, an ignition coil, a breaker and distributor finger assembly timed to said engine and electrically connected to said ignition coil, a top for said breaker and distributor finger assembly having a plurality of contacts therein evenly spaced around said distributor finger and adjacent to the path described by the end of said distributor finger, a plurality of spark plug contacts arranged around said top; said spark plug contacts being twice as numerous as said distributor contacts, leads connecting the spark plugs in each cylinder to adjacent ones of said spark plug contacts, a switch plate moveably secured to said top, a plurality of contact plates secured to said switch plate; each of said contact plates selectively connecting both of the spark plug contacts for one cylinder to one of said distributor finger contacts and only one of said spark plug contacts to said distributor finger contact, a housing secured to said top, a diaphragm in sealed relation with said housing producing an air-tight chamber, a linkage connecting said diaphragm to said switch plate, and a conduit communicating between the interior of said housing and the intake manifold of said internal combustion engine.

4. In an automatic spark plug switch for use with an ignition breaker and distributor finger assembly, a top adapted to being secured to an ignition breaker and distributor finger assembly, a. plurality of distributor finger contacts secured to and extending through said top, a plurality of spark plug contacts secured to said top and being twice as numerous as said distributor finger contacts; one of said distributor finger contacts and two of said spark plug contacts constituting a group, a switch plate moveably secured to said top, a plurality of contact plates secured to said switch plate and each selectively contacting all the contacts of one group or omitting one spark plug contact from each group, a housing connected to said top, a diaphragm in said housing and in secured to in sealed relation to form an air-tight chamber, linkage connected to said diaphragm and said switch plate, and a conduit having one end secured to and in communication with the interior of said housing in the portion forming an air-tight chamber, and means secured to the other end of said conduit adapting it to be secured to and in communication with the intake manifold of an internal combustion engine.

5. In an automatic spark plug switch, a contact support member, a plurality of spark plug contacts secured to said contact support member, a plurality of distributor finger contacts secured to said contact support member, a switch plate moveably secured to said contact support plate; said spark plug contacts being twice as numerous as said distributor finger contacts, a plurality of contact plates secured to said switch plate, and a movement producing means responsive to changes in engine load conditions secured to said switch plate.

6. In an automatic spark plug switch, a contact support member, a plurality of spark plug contacts secured to said contact support member, a plurality of distributor finger contacts secured to said contact support member, a switch plate moveably secured to said contact support plate, said spark plug contacts being twice as numerous as said distributor finger contacts, a plurality of contact plates secured to said switch plate, a housing secured to said contact supporting member, a diaphragm in sealed relation to said housing and forming an air-tight chamber, a conduit connected to said housing and communicating with said air-tight chamber, linkage connecting said diaphragm to said switch plate, and a means on the other end of said conduit for connecting it to and in communication with the intake manifold of an internal combustion engine.

7. In a spark plug switch, a contact support member, a plurality of spark plug contacts secured to said contact support member, a plurality of distributor finger contacts secured to said contact support member, a switch plate moveably secured to said contact support plate; said spark plug contacts being twice as numerous as said distributor finger contacts, a plurality of contact plates secured to said switch plate, and a means secured to said switch plate for moving it.

DAVIS H. SAUNDERS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,465,080 Fitzsimmons Mar. 22, 1949 

